The present invention relates generally to a base for use with apparatus sensitive to horizontal vibration, and more particularly to a base that supports a generally horizontally reciprocating member and associated drive means normally operative to impart horizontal vibration to the base during operation, and includes novel means for substantially nullifying horizontal vibration forces imparted to the base by the reciprocating member.
It is a common practice in many types of apparatus and machines to connect an operating mechanism, such as a print head or the like, to a base so that the print head defines a work station at a desired height above the floor surface for convenient operation and operator comfort. The operating mechanism may be directly supported by the base, or may be freestanding but in operative association with the base. In those instances where the operating mechanism is sensitive to horizontal vibration, such as an ink jet printer mechanism, it is important that horizontal vibration of the base be minimized so as not to adversely interfere with proper printer operation. For example, ink jet printers project droplets of ink generally vertically downwardly onto a surface, such as a mailing envelope or other document, in a predetermined pattern to create a mailing address or other printed indicia. In commercial printing, the envelopes or other documents are generally fed in sequential one-at-a-time fashion along a horizontal path from a vertical stack of envelopes or documents to a position underlying the printer head by feeder means including a reciprocating shuttle or feeder plate. Drive means are cooperative with the shuttle plate to effect horizontal reciprocating movement thereof between a position operative to remove successive documents from the bottom of the stack and a position wherein the leading edge of each document enters a nip between feed rolls which advance the document onto transfer means for carrying the document to the printer head.
With apparatus or machines of the aforedescribed type, as the reciprocating shuttle plate reaches the end of each stroke, the momentum of the shuttle plate and the reaction force imparted to the base by reversal of the shuttle plate causes horizontal deflection of the base. This generally results in horizontal vibration of the printer head, if supported on the base, and thereby adversely effects proper operation of ink jet type printer mechanisms by significantly altering the print pattern. Proper operation of the ink jet printer mechanism is also adversely effected where the ink jet printer head is freestanding but overlies document transfer means supported on the base.
One solution to this problem is to make the base sufficiently heavy and rigid so that the forces imparted to the base by the reciprocating shuttle plate are resisted by the mere mass of the base, thus substantially nullifying horizontal vibration otherwise imparted to the printer head or to the document transfer means. This solution, however, is costly and results in a base substantially heavier than desired.